I have a lot of red oaks and hickorys now growing on my property along the fences. The acorns and nuts from the mature trees, quite surprizingly, start up new ones every year which I transplant to other parts of the property. I tend to put them about at every fence post(8-10') so I can keep tract of where they are when mowing. Every year I start another line of them, also about 8-10' apart. After a few years of this, I have quite an array of trees. Certainly no closer because when they are older (and I'm at the end of my rope), I can still run a decent lawn mower around them. Although pines are my favorite, the oaks and hickorys are more native to my location and certainly more durable. For some reason, I have never had any luck with planting nuts, so I wait for them to sprout and transplant them after they are about a foot tall. That only takes 2 years in the very wet, soggy black loam thay start up in. I usually have to fight the squirrels off to get nuts, but maybe its them that are making the new growth appear.